Cured in place underground pipe repairs have conventionally involved the application of an adhesive bonding substance or other hardenable coating substance to a flexible sleeve or liner. The coated liner is installed within an old, deteriorated, cracked and/or ruptured pipe and allowed to cure in place to effectively repair or refurbish the pipe. This manner of underground pipe and conduit repair is described, for example, in my U.S. Pat. Nos. 4,995,761 and 5,049,003. Traditionally, manhole-to-manhole underground pipe repairs have been performed using a styrene resin as the bonding product. Styrene is toxic, flammable and environmentally unfriendly. As a result, its use in underground conduit repair has been banned in a number of states and is liable to become illegal nationwide in the future.
Alternatively, epoxy resin has been used for cured in place liners. This product is less toxic and flammable, yet stronger than styrene resin. However, epoxy resin and other hardenable coating materials are often very difficult to work with and can be particularly problematic to apply to the liner in a thin, uniform, effective and efficient manner. Conventionally, a large mass of epoxy resin is applied at one end of the cylindrical liner sleeve while the opposite end is vacuumed. The sleeve is then rolled or otherwise worked to spread the epoxy throughout the liner. Such a large mass or lump of epoxy tends to cure fairly quickly, thereby making it very difficult, if not impossible, to apply the epoxy uniformly to the liner. Not only is hardenable product wasted, the resin mass is apt to react and cure before the liner is completely impregnated and installed in the pipe. In some cases, the resin may cure so quickly that the liner is rendered wholly ineffective for use in performing the necessary repairs. This problem is especially acute when the epoxy must be applied to extended liners required for performing lengthy (e.g. 200 foot) manhole-to-manhole repairs.
A system has been developed wherein holes are cut in the liner to introduce epoxy resin into selected spots or locations along the liner. This reduces the problem of applying the epoxy in a mass or lump. However, cutting holes in the liner compromises the integrity of the liner and requires repair of the cut holes themselves.